Handling Cell Reselections and State Transitions for High-Speed Downlink Packet Access

1. A method for cell reselection implemented by a wireless transmit receive unit (WTRU), the method comprising: defining a single high speed downlink shared channel (HS-DSCH) reception variable (HS_DSCH_RECEPTION_GENERAL) indicating the status of HS-DSCH reception for the following states: Cell_FACH, Cell_PCH, URA_PCH and Cell_DCH; setting the HS_DSCH_RECEPTION_GENERAL variable to TRUE on the condition that HS-DSCH procedures are ongoing; setting the HS_DSCH_RECEPTION_GENERAL variable to FALSE on the condition that a new cell following a cell reselection does not support HS-DSCH reception; and releasing HS-DSCH resources on the condition that the new cell does not support HS-DSCH reception.

2. The method as in claim 1 , wherein releasing HS_DSCH resources comprises: stopping high speed synchronization control channel (HS-SCCH) reception; stopping high speed downlink shared channel (HS-DSCH) reception; clearing radio network temporary identifiers (RNTIs); resetting a medium access control (MAC) entity; releasing hybrid automated response request (HARQ) resources; and clearing any stored information elements related to HARQ information.

3. The method as in claim 1 , further comprising reading a medium access control (MAC) state indicator to determine HS-DSCH reception.

4. The method as in claim 1 , further comprising reading an information element (IE) to determine HS-DSCH reception status in at least one of the following: system information block (SIB) type 5 or SIB type 5bis.

5. The method as in claim 4 , wherein the IE is HS-DSCH common system information.

6. The method as in claim 4 , wherein the IE is HS-DSCH paging system information.

7. A wireless transmit receive unit (WTRU) comprising: a processor configured to: define a single high speed downlink shared channel (HS-DSCH) reception variable (HS_DSCH_RECEPTION_GENERAL) indicating the status of HS-DSCH reception for the following states: Cell_FACH, Cell_PCH, URA_PCH and Cell_DCH; set the HS_DSCH_RECEPTION_GENERAL variable to TRUE on the condition that HS-DSCH procedures are ongoing; set the HS_DSCH_RECEPTION_GENERAL variable to FALSE on the condition that a new cell following a cell reselection does not support HS-DSCH reception; and release HS-DSCH resources on the condition that the new cell does not support HS-DSCH reception.

8. The WTRU as in claim 7 , wherein the processor is further configured to: stop high speed synchronization control channel (HS-SCCH) reception; stop high speed downlink shared channel (HS-DSCH) reception; clear radio network temporary identifiers (RNTIs); reset a medium access control (MAC) entity; release a hybrid automated response request (HARQ) resources; and clear any stored information elements related to HARQ information.

9. The WTRU as in claim 7 , further comprising reading a medium access control (MAC) state indicator to determine HS-DSCH reception.

10. The WTRU as in claim 7 , further comprising reading an information element (IE) to determine HS-DSCH reception status in at least one of the following: system information block (SIB) type 5 or SIB type 5bis.

11. The WTRU as in claim 10 , wherein the IE is HS-DSCH common system information.

12. The WTRU as in claim 10 , wherein the IE is HS-DSCH paging system information.